Production of refractory metal alloys



B. .D. SAKLATWALLA AND A. N. ANDERSON.

PRODUCTION 0F REFRACTORY METAL ALLOYS.

APPLICATION HLED APR. 8. 1920.

1,435,742. Patented Nov. 14, 1922.

.4M /MJMMA Patented Nov. 14, 1922.

UNITED `STATES lP'tATl-EIFJ'I' OFFICE.

BYRAMJ'I D. SAKLATWALLA AND ARTHUR N. ANDERSON, OF GRAFTON, PENNSYL- VANIA, -ASSIGNORS TO VANADIUM CORPORATION OF AMERICA, OF A:BRIDGE- V'ILLE, PENNSYLVANIA, A CORPORATION OF DELAWARE.-

PRODUCTION OF REFRACTORY METAL ALLOYS.

Application led April 8,

To all whom t may concern:

Be it known that we, BYRAMJI D. SAK- LATWALLA and ARTHUR N. ANDERSON, residing at Crafton, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in the Production of Refractory Metal Alloys, of which the following is a full, clear, and exact description,reference being had to the accompanying drawing forming partof this specication, in whic the ligure is a diagrammatic longitudinal vertical section of a furnace designed' for carrying out our invention.

Our invention relates to the forming of the alloys of hi hly refractory metals, such as vanadium. eretofore, it has been considered necessary to use metallic reducing agents, such as silicon or aluminum, in the forming of alloys from ores or materials containing the highly refractory metals.

We have discovered a successful, practical process for forming such alloys of vanadium and other high heat refractory metals by the use of carbon as a reducing agent in electric furnace treatment.

In our preferred form of process, there are three factors of importance, which We will now recite in the order of 'their importance.

1. A critical voltage. We have found it important, if not essential, in commercial manufacture of such alloys of hi h refractory metals to employ a voltage o one hundred and fifty volts or more with an electric furnace of commercial size; and we have also found that lthere isa critical current density of at least thirty-five amperes per square inch of cross section of electrodes, we having used a density of from'zthirty amperes t0 about ninety amperes per square inch of iso cross section of electrode. This refers to the alternating current, which we preferably employ.

2. Spacing of electrodes where a plurality of electrodes is employed,`as in our preferred form. Takingthe diameter of an electrode or its thickness in the direction of the next electrode, the spacing between electrodes should lie between 1 and 1.50 of this unit, with the use of the proper resistance of the 1920. Serial No. 372,169.

bath to regulate the arcs, obtained as hereinafter described.

3. Feeding the charge between the electrodes. Byfeeding the charge downwardly between the electrodes where a plurality are used,l as in our preferred form, the charge is carried directly into the reaction zone and the reduced metal and slag carried away by gravity from that zone and the swirl set upv by the effect of the electric current.

By feeding the charge directly into the high temperature reaction zone, the charge is not subject to any substantial preheating or partial reduction previousto its reduction in the high temperature reaction zone. Thisdirect feeding into the high temperature reaction zone 1s particularly important in smelting vanadium and similar ores in which it is highly desirable that the higher oxides of the ore be reduced directly to the metallic state without preformationof lower oxides.

'In all 6cases, the dependin electrode 'or electrodes should terminate a ove the level of the metal of the reduced alloy lyin below the slag layer, the heat effect being o tained by means of the arc through the charge and through the slag above the metal layer.

Referring now to the drawing, in which we show diagrammatically a preferred form of apparatus for carrying out our invention, 2 represents the metal shell or casing of an electric furnace having a carbon lining 3. This lining ma be made of either amorphous or graph1tic carbon or both, it being shaped to form a central cavity for the bath. Above the lining is a refractory cover 4, preferably formed of refractory brick, with water-cooling devices embedded therein, through which water is circulated. This re,- fractory cover is provided with a hole or holes, preferably lined with annular watercooling devices, indicated at 5, through which depend the electrodes 6, which fit closely therein, the furnace chamber being preferably substantially air-tight. In the form shown, there are three electrodes each connected to the lines 7 of a three-phase alternating current supply, which is above one hundred and fifty volts and of high current density, as above recited. The electrodes are could be used at the center of the triangle, discharging into the region between the elec trodes.

The drawing illustrates diagrammatically the layers of materials' as in regular operation, and the temperature zone. Thus, A

' represents the lower layer of molten alloy which may be tapped out from time to time through the tap hole 9. The outer portions A of this layer are shown as congealed or partly congealed. Above this molten metal ayer is the layer B of slag with the charges entering it between the electrodes, as indicated. This slag zone is shown as having a dished or concave surface, which is somewhat exaggerated in thedrawing. This surface is due to the swirling or whirlpool action of the molten bath or the upper portion thereof,

resulting from the action of the electric cur rent, and it will be noted that the charge feed is into the central portion of this swirl. The dotted lines X-X indicate the zone of highest temperature under the conditions shown, within which zone the reducing action takes place, this temperature zone being surrounded by the outer slag annulus B.

In forming a vanadium alloy, the charge is a mixture of pulverized vanadium ore, or vanadium-bearin material, such as vanadium oxide or su phide, iron, preferably in the form of iron scale or iron lore, and fiuxes, such as glass cullet, lime, liuorspar and coke.

' The glass cullet or similar flux has two im-v portant functions: lst, to increase the electric resistance; and second, to control the speed of the whirl by increasing the viscosity of the slag, and thus reducing the washing effect on the lining. The iron scale also serves to increase the electric resistance, and hence serves to regulate the length and localization of the arc; and also as it is reduced, forms the alloy of ferro-vanadium desired. The commercial ferro-vanadium product now in demand contains about 30% to 40% of vanad ium, and we have made such alloys as hlgh as 50% vanadium.

As an example of the mix underthe conditions herein recited, we have used from one to five per cent of cullet and from two per cent of iron scale for low gradeore up to fifteen per cent for high grade ore, coke also being-added. i

In c ase the gangue constituents of ore or vanadlum-containing material have uxes and constituents somewhat similar to that of glass cullet, the cullet need not be added. These percentages, will depend to a considerable extent upon the chemical composition of the ore or vanadium-bearing material.

Underthe conditions shown and recited, taking the electrode diameter as a unit, the distance between electrodes is about 1.25. The distance from the outer electrodes tov the edge of the bath is shown as 2 and may vary from 2 to 3, and the over-all diameter of the bath is about 9.50, the current being over 150 volts and with a density of between 35 and 50 amperes per square inch of electrodes in cross section. The slag may be drawn off through the slag tap 10. As the operation goes on, the entering charges fed in between the electrodes enter the best zone of reduction and are drawn down by the swirling action. The ends of the electrodes lie in the slag layer above the metal layer, and-reduction is rapid and effective under the conditions named. We have found that vanadium reduction demands a very high temperature, a quick reaction and a uick removal from the zone of reaction. he reaction is -highly localized by something like a blowipe effect. The drawing is scaled to the preferred relative areas employed under the conditions named as to voltage and density, character of mix, arrangement of electrodes, with three-phase current, etc.

The current is preferably controlled by a control system, such as that shown, for example, in our co-pending applications, Serial Nos. 292,285 and 292,28e,fi1ed April 24, 1918. The alloy formed containsabout 30 to 40% of vanadium, the remainder being iron with certain metals ,or metalloids, such as silicon, manganese and carbon. 4

The advantages of our invention will be apparent to those skilled in the art, since we believe' that we are the first to attain the productionA of vanadium alloys without the use of metallic reducin agents. A reduction of carbon has been e'sired, and has been attained by'us by means of the process above recited.

The important features of the process may be carried out with less efliciency, however, by the use of a single electrode, or upper and lower electrodes with a single'or multiphase current. If a single electrode is used, the

current should be at least 150 volts and above the lower amperage limit of 35 amperes, per square inch of electrode. In such case, the feed should be as nearly as possible to the ba'se'of the electrode.

The vanadium-bearing material may be varied, the form of carbon used may be changed, the fluxes may be varied so long as proper electrical resistance to regulate the arc is obtained in the slag layer, the number and arrangement of the electrodes may be changed, and other variations may be made,

without departing from our invention, as defined in the broader claims.

IVe claim:

1. In the method of forming alloys of highly refractory metals, the steps consisting of reducing the metal in an electric furnace under a voltage of more than 150 volts, substantially as described.

2. In the method of forming alloys of highlyv refractory metals, the steps consist-l ing of reducing the metal in an electric furnace under a voltage of more than 150 volts and of at least 35 amperes per square inch of electrode area, substantially as described.

3. In the method of forming alloys of highly refractory metals, the. steps consisting of feeding charge material into a plural electrode furnace having a spacing between the electrodes of 1 to 1.5, based on the thickness of an electrode as a unit, substantially as described.

4. In the method of forming alloys of highly refractory met-als, the steps consisting of feeding charge material into an electric furnace having an electric current supply of at least 150 volts and of high current density, with a spacing between the electrodes of 1 to 1.5 based on the thickness of an electrode as a unit, substantially as described.

5. In the here-in described method, the steps which consist in maintaining in the hearth of an electric furnace a molten bath int-o which the furnace electrodes extend and produce between them a high temperature reaction zone, and in feeding directly into such reaction zone highly refractory metalbearing material and car onaceous material, substantially as described.

6. In the method 'of forming alloys of highly refractory material, the steps consisting of feeding a charge in the region between a plurality of electrodes of an electric furnace, and' supplying current to the electrodes of at least 150 volts, substantially as described.

7. In the method of forming alloys of highly refractory material, the steps consisting of feeding a charge in the region between a plurality of electrodes of an electric furnace, and supplying current to the electrodes of at least 150 volts and at least 35 amperes per square inch of electrodes, substantially as described.

8. In the herein described method, the steps which consist in maintaining in the hearth of an electric furnace a molten bath having a slag layer into which the furnace electrodes extend and produce between them a high temperature reaction zone, and in feeding directly into such reaction zone highly refractory metal-bearing material and carbonaceous material, substantially as described.

9. In the method of forming alloys of highly refractory material, the steps consisting of feeding a charge containing high refractory metal-containing material, carbonaceous material, and fluxing material andv alloyin material into the region between the electro es of an electric furnace having a current suppl of at least 150 volts, subs-tantially as diescribed. r

l0. In the methodof forming alloys of highly refractory material, the steps consisting of feeding charge-forming material downwardly between the electrodes of a plural-electrode furnace having a spacing between the electrodes of 1 to 1.5 based on the thickness ofthe electrode as a unit, and supplying a current of at least 150 volts, substantially as described.

11. In the method of forming alloys of highly refractory material, the steps consisting of feeding into the region between the electrodes of a plural-electrode furnace a mixture of vanadium-containing material, alloying material. and carbonaceous material, and supplying to the electrodes a current of at least 150 volts with acapacity of at least 35 amperes per square inch of electrodes, substantially as described.

12. In the method of forming alloys of highly refractory material, the steps consisting of feeding into the region between the electrodes of a plural-electrode furnace a mixture of vanadium-containing material, alloying material and carbonaceous material, and supplying to the electrodes a current of at least 150 volts with a capacity of at least 35 amperes per square inch of electrodes, the electrodes being spaced apart fro-m 1 to 1.5 based on the thickness of an electrode as a unit, substantially as described.

13. In the method of forming alloys of highly refractory material, the steps consisting of maintaining a lower bath of molten alloy with an upper layer of slag in a pluralelectrode furnace, feeding a mixture containing vanadium-bearing material into the region between the electrodes which terminate above the molten metal layer, and supplying a current of at least 150 volts, substantially as described.

14. In the method of forming alloys of` highly refractory material, the steps consisting of maintaining a lower bathl of molten allo-y with an upper layer of slag in a pluralelectrode furnace, feeding a mixture containing vanadium-'bearing material into the region between the electrodes whichterminate above the molten metal layer, and supplying a current of at least 150 volts and at least 35 amperes per square inch of electrodes, substantially as described.

15. In the method of forming alloys of highly refractory material, the steps consisting of maintaining a lower bath of molten alloy with an upper layer of slag in a plural- ,electrode furnace, feeding a mixture containing lvanadium-bearing material into the 17. In the herein described method, the

step which consists in feeding a mixture containing a vanadium-bearing material, a fluxing material, and ycarbonaceous material directly into the high temperature reaction zone of an electric smeltlng furnace, substantially as described.

18.'I In' the herein described method, the step which consists in feeding a mixture containing a vanadium-bearing material, an alloyng metal-bearin material, and carbonaceous material directly into the high temperature reaction zone of an electric smeltin furnace, substantiall as described.

19. e method of reduclng vanadium containing materials, which consists in maintaining in the hearth of an velectric furnace a molten bath into which the furnace electrodes extend and produce vbetween them a high temperature reaction zone, and lin feeding directly into such reaction zone a vanadium containing material and carbonaceous material, subst'antiall as described.

20. The method o; containing materials, which consists in elec-- trically smelting such materials to the metallic state with a carbonaceous reducing agent, substantially as described.

21. The method of reducing vanadiumcontaining materials, which consists smelting such materials to the metallic state with a carbonaceous reducing agent, substantially as described.

22. The method of making ferro-vanadium, which consists in electrically smelting iron and vanadium-containing materials to the metallic state with a carbonaceous reducing agent, substantiall as described.

23. The method of lre ucing vanadiumcontaining materials, which consists in maintaining in the hearth 4of an electric furnace a molten bath having a slag layer into which the furnace electrodes extend and produce between them a high temperature reaction zone, and in feeding directly into such reducing vanadiuminv bath having a localized high temperature reaction zone, in feeding directly into such reaction zone a vanadium-contamin material and carbonaceous material, hol 1n the materials in such zone until the van ium is reduced to the metallic state, and removing the reduced vanadium metal. fromsuch zone by gravity, substantially as described.

26. The method of making ferro-vanadium, which consists in maintaining in the hearth of a furnace a molten bath having al localized high temperature reaction zone,

and in feeding 'directly into such reaction4v zone iron and vanadium-containing materials and carbonaceous material, substantially as described.

27. The method of making ferro-vana-l dium, which consists in maintaining in the hearth of a furnace a molten bath having a localized hightemperature reaction zone, in feeding directly into such reaction zone iron and vanadium-containin materials and carbonaceousy material, lho ding the materials in such zone until the vanadium and iron are reduced to metallic ferro-vanadium, and removing. the reduced ferro-vanadium metal from such zone by gravity, substantially `as described.

28. The method o f reducing vanadiumcontaining materials, which consists in smelting such materials to the metallic state Witha carbonaceous material and a lluxing material, substantially as described.

29. The method of making ferro-vanadium which consists in smelting iron and vanadium-containing materials to the metallic state4 with a carbonaceous reducing agent and a lluxing material, substantially as described.

In testimony whereof, we have hereunto set our hands.

BYRAMJ I D. SAKLATWALLA. ARTHUR N. ANDERSON.' 

